/**
 * @program: leetcode617
 * @author: JCM
 * @create: 2022-11-19 09:18
 * @description: 合并二叉树
 **/

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
}
public class leetCode617 {

}
class Solution {
    public TreeNode mergeTrees(TreeNode root1, TreeNode root2) {
        if(root1 == null && root2 != null) {
            return root2;
        }else if(root2 == null && root1 != null) {
            return root1;
        }else if(root1 == null && root2== null) {
            return null;
        }else {
            root1.val = root1.val+root2.val;
        }
        root1.left = mergeTrees(root1.left,root2.left);
        root1.right = mergeTrees(root1.right,root2.right);
        return root1;
    }
}
